A.H. Chaney

Bio: A.H. Chaney is an academic researcher. The author has contributed to research in topics: Turtle (robot) & Chelydra. The author has an hindex of 3, co-authored 4 publications receiving 72 citations.

Turtle Populations in Louisiana

Abstract: The role of turtle populations in fresh water biology has been generally ignored although these animals may, in some areas, be the dominant vertebrates. Available information is inadequate to define precisely the relation of any turtle population to that of another animal. Analysis of the significance of aquatic turtle populations in fresh water requires information on the abundance and habitat preferences of each species. Trapping provides the best basis for estimating this information. Traps are unsatisfactory in that they are selective for certain size groups of each species and catches vary with the type of bait, method of set, water temperature, and water depth. Too, the first individual to enter a trap may determine the nature of the total catch. Thus a large Chelydra or Macrochelys in a trap will often prevent others from entering, and a female will attract males during the periods of sexual activity. Such factors must be considered when utilizing trap returns in population studies. Hand collecting tends to produce an abundance of Pseudemys, Chrysemys, and Graptemys but few A myda, Macrochelys, or Chelydra. Regardless of these factors in trapping, which cannot be evaluated at present, trap results are the best basis for determining relative abundance. Turtle traps were operated in 14 water bodies in Louisiana during the summer of 1947 (Fig. 1). The traps were made of 1" square mesh netting suspended on three 36" diameter steel hoops. An adjustable net throat was attached at one end and a draw string outlet at the other. Bamboo poles were used to spread the three hoops and to hold the traps in place. Bait (fresh gar, bowfin, catfish) was suspended in a can just in front of the open throat.

Use of Dredged Material Islands by Colonial Seabirds and Wading Birds in Texas.

Abstract: : The purpose of this study was to aid personnel of the U.S. Army Corps of Engineers in assessing the environmental impact of dredged material disposal sites by gathering information on those islands in Texas waters. Thirty-four islands were selected for detailed study, 17 in the Galveston-Houston area and 17 in the upper Laguna Madre near Corpus Christi. The following investigative activities were concluded: (1) the islands were photographed, visited by boat, and measured as to elevation and area; (2) over 3000 soil samples were taken; (3) the vegetation on each island was identified, measured, and quantified in over 3000 quadrats; (4) plant communities were identified and vegetation maps of each island were constructed; (5) birds using the islands as nesting sites were identified and their nests were monitored; (6) location of colonies was plotted on island maps and nesting information was summarized and placed in tabular form; (7) islands, birds, and vegetation were related to each other and discussed; (8) the numbers and species of nesting birds were compared with those nesting on natural sites in each area and for the entire Texas coast; and (9) recommendations were made concerning island construction, maintenance, and management in relation to nesting seabirds and wading birds.

A contribution to the herpetology of northern coahuila, mexico

Abstract: Collections and reports of amphibians and reptiles from Ciudad Melchor Muzquiz to Boquillas del Carmen in northern Coahuila, Mexico, are discussed. Bufo cognatus, Gastrophryne olivacea, Scaphiopus hammondi hammondi, Kinosternon f/avescens {lavescens, Coleonyx brevis, Crotaphytus collaris x reticulatus, Eumeces tetragrammlJs brevilineatus, Phrynosoma modestum, Sceloporus undulatus consobrinus, Lampropeltis triangulum annulata, Sonora episcopa episcopa and Tantilla planiceps atriceps are either new or from new localities in area. Leptodeira septentrionalis septentrionalis and Opheodrys aestivus are new genera for the state of Coahuila and are interpreted as additional members of the relics in the Chihuahua-Zacatecas Biotic Province of Coahuila. Trans. Kansas Acad. Sci., vol. 80 (1-2),

Ecology of the Basking Habit in Turtles

Abstract: A combined field and laboratory study was conducted to assess the biological implications of the basking habit in turtles. The effect of light intensity and incidence angle, water and air temperatures, wind, and cloud cover upon rates of heat gain in turtles were investigated, and all were found to have importance. Biological factors of importance are behavior, shape, weight, and rarely, color; sex and species were not important except as they affect the other factors. A series of motivation studies was conducted to identify the environmental factors initiating and directing basking. The taxonomic incidence of the basking habit in turtles is discussed. Basking serves primarily as a method of thermal control, with secondary benefits in drying of the skin and shell. See full-text article at JSTOR

The Evolutionary and Mathematical Demography of the Turtle Chrysemys picta

Abstract: A mark—recapture study of a population of painted turtles, Chrysemys picta, started by O. J. Sexton between 1953 and 1957 was continued between 1968 and 1973. Life tables are constructed and a demographic history of the population is suggested. Males mature during their 4th yr and first breed at age five. Females mature at age seven and lay two clutches of about 6 to 7 eggs each year. Mortality is about 92% between laying and the arrival of the hatchlings at the pond. Juvenile and adult mortality is at a constant exponential rate of about 0.15 for males and 0.18 for females each year. Raccoons, Procyon lotor, are an important predator during spring migrations. There is no indication of senescence; females over 30 yr old are still reproductive. Between 1954 and 1972 the population's size has been reduced from an estimated 981 to about 186 animals. This has been accompanied by a decrease in mean generation time from 12.35 to 10.70 yr. Survivorship from laying to arrival at the pond has more than doubled, but adult survivorship has decreased. These changes are attributed to an increased predation rate resulting from a reduction in the number of safe basking sites. A hypothetical population was simulated by recurrent use of a population projection matrix, derived from the 1954 life table, to demonstrate the stability characteristics of this long—lived, iteroparous species. The evolution of this life history is interpreted as an adaptation to a highly uncertain probability of nest success and an effective predator defense in the adult stage.

The Influence of Sampling Methods on the Estimation of Population Structure in Painted Turtles

Abstract: A natural population of painted turtles [Chrysemys picta (Schneider)] was studied in University Bay of Lake Mendota, Dane County, Wisconsin, from September 1960 to October 1962. Five methods were used to capture turtles for marking, measurement, and release. Each of the methods yielded a different size-class distribution and a sex ratio which, in four out of five cases, was significantly different from that of the total population estimate. Baited hoop nets yielded predominantly males and relatively few juveniles; basking traps tended to yield higher percentages of females than did nets, and large turtles were an important component of the sample. Hand capture resulted in a sample heavily weighted by juveniles and a 1: 1 sex ratio for adults. The influence of trapping method in the estimation of population structure in turtles must not be overlooked. This study indicates that even within a species, trapping method introduces considerable bias in the estimation of sex ratio and size-class distribution. INTRODUCTION The structure of turtle populations, as estiimated by different authors (Cagle, 1942, 1944, 1954; Pearse, 1923; Sexton, 1959), has varied considerably even within the same species. Although this variation may be due to inherent differences in the populations studied, or to various ecological factors affecting each population with different intensities, it is more probable that the disparity lies in the sampling method used by the investigators. Cagle and Chaney (1950) suggested that sampling methods are biased by the behavioral patterns of the size classes and sexes that make up the population, but we are unaware of any study that has compared the variation in estimation of population and its strutcture brought about by use of different sampling methods. A natural population of Chrysemys picta (Schneider) was studied in University Bay of Lake Mendota, Dane County, Wisconsin, from September 1960 to October 1962. The central painted turtle, Chrysemys picta marginata (Agassiz) and the western painted turtle, Chrysemys picta belli (Gray) intergrade in this region (Pope, 1949). Five methods were used to capture a maximum number of turtles for marking, measurement, and release. Variant results obtained from use of these methods were sufficiently striking to, warrant a comparison of the methods. Acknowledgments.-This study was done with the aid of two NSF Summer Fellowships for Teaching Assistants. Additional financial assistance for field equipment and limited field assistance was provided by a grant to Dr. W. G. Reeder from the Wisconsin Alumni Research Foundation through the University of Wisconsin Graduate School. Appreciation for encouragement and constructive criticism is given to Dr. W. G. Reeder, Dr. J. M. Legler, and Dr.

Accuracy and variation in estimates of large numbers of birds by individual observers using an aerial survey simulator

Abstract: The accuracy of aerial estimates of avian aggregation sizes is variable across studies, and the relative importance of techniques and inter-observer error to this variation are poorly understood Using a scaled physical model of a wading bird colony, we examined accuracy and variation in observer counts of simulated large numbers (200–6000) of densely nesting birds in vegetated situations Observer estimates averaged 29% less than true numbers (under- and overestimates averaged together), and the mean absolute value of observer errors was 49% of true values We found no effects of the size of the aggregation, the experience of the observer, the size of the previous aggregations surveyed by observers, the use of corrective lenses, or fatigue on degree of individual error Over- and underestimates by individuals did not tend to cancel out in estimates by individuals of a “population” of colonies Photographic counts of the same trials were significantly more accurate than observer estimates We suggest that many studies using estimates of large numbers of birds may be confounded by similar errors We urge that researchers use caution in interpreting the results of past surveys and develop ways to minimize, measure, and correct for visual estimation error within individuals and among observers